an autodidact meets a dilettante…

a product of doubtful value

Now it’s time to get back to some sceptical enquiry. Here I want to look at what are called A1 milk and A2 milk, to identify the differences between them and to analyse claims about health benefits or otherwise, including questions of food intolerance. These are issues coming up with a few people close to me, and I’d like to step back and obtain a more detached, evidence-based view.

Before I start, there’s an interesting account here about the reporting in Australia [by the ABC, no less] about the alleged benefits of A2 milk. I wouldn’t be surprised if this positive but not particularly critical reporting on A2 milk has influenced the views of members of my family. So what does the science really tell us?

A1 and A2 refer to different forms of beta-casein, a protein that account for 80% of all the proteins in milk. Generally, milk contains a mixture of both forms. The A1 form of beta-casein releases, in the process of digestion, and also during the processing of milk, the peptide BCM7 [beta-casomorphin-7]. This peptide is claimed, by such promoters of A2 milk as Freedom Foods, to be a strong opioid which can adversely affect mucus production and other processes in the gut. A2 milk has also been promoted as [to varying degrees] preventative of autism, schizophrenia, diabetes and heart disease. The consumer organisation, Choice, however, has this to say [on a website dated September 2009]:

However, the European Food Safety Authority recently reviewed the science and found no justification for claims about the health risks from BCM7. Food Standards Australia New Zealand is similarly sceptical about the evidence for the claims for A2 milk.

The ABC’s most recent venture into this issue was on its 7.30 Report in July 2010. Basically it was a rehash of the claims made by Freedom Foods, with the only new piece of science being a Russian paper claiming developmental delays in babies fed A1 formula, which correlated with high levels of BCM7. The Australian dietician Professor Peter Clifton – co-author of the CSIRO diet books – described the paper as flawed ‘for many many reasons’. He felt that the researchers didn’t measure what they claimed to measure.

All this excitement about A2 milk apparently first began in New Zealand over a decade ago [though sceptical voices were raised early too], and one of the strongest advocates of A2 milk’s prophylactic properties has been Keith Woodford, a Professor of Farm Management and Agribusiness at NZ’s Lincoln University. His book, Devil in the Milk, was published in the USA in 2007, having been published earlier in New Zealand. In fact, A2 milk is only currently available in New Zealand and Australia, and to a much lesser extent in the USA. The book has become something of a cause celebre amongst ‘natural health’ and ‘raw milk’ obsessives, as can be seen by this post and all the comments it attracts, but the more I look into the subject of A2’s benefits, the foggier the issues become.

The theory goes [but even this has been questioned] that in earlier times all cows [and goats, sheep, camels and buffaloes] produced A2 milk, but that some 5000 years ago a mutation occurred, in which the amino acid histidine replaced the amino acid proline in postion 67 of the chain of 209 amino acids that make up the beta cassein protein, and that this small mutation is possibly responsible for all sorts of negative physiological effects. A lot of the claims against A1 milk appear to be based on statistical studies correlating its consumption with increased incidence of heart disease and other ailments – including autism, as claimed by some. There are many ‘red flags’ associated with this sort of correlation. Correlation doesn’t by any means prove causation, and there are many confounding factors obscuring the connection between correlation and causation here. A1 milk is consumed in most western countries where such ailments as heart disease and diabetes are already correlated with increased cholesterol and triglycerides due to diets high in saturated fats and sugar. The link between correlation and causation seems clearer for these chemical compounds. As for autism, clearly a neurophysiological disorder, it’s surely highly unlikely to be caused by peptides in the gut, and the passing on of those peptides to offspring. An article in the most recent edition of Cosmos magazine describes autism as ‘90% genetic’.

There’s not much more to say, without closer analysis of the the claims made by Woodford and others, and I don’t have easy access to the details. It might be that further research will provide some support for claims against BCM7, but it looks highly unlikely that a clear-cut case will be made for its villainy, and out of this fog of endless contestability conspiracy theories and fanaticisms are bound to arise. In any case I see no good reason to jump on the A2 bandwagon, or to advise anyone else so to do.